Lifting-jack with rotatable cams



A. PETELER.

LIFTING-JACK WITH ROTATABLE CAMS.

APPLICATION FILED AUG.22,1919.-

1,352,472, v PateHtedISeptI I, 1920.

2 SHEETS-SHEET l- I IIII dd WM; m Z

A. PETELER.

LIFTING JACK WITH ROTATABLE CAMS.

APPLICATION FILED AUG.22. 1919.

1,352,472. PatentedSpt. 14,1920,

2 SHEETS-SHEET 2.

UNITED STAILELS AnoLPrr PETELER, or FREEPORT, ivnw YORK.

LIFTING-J 'AGK WITH ROTATABLE CAMS.

Specification of Letters Patent. Patented Sept. 1920.

Application filed August 22, 1919. Serial No. 319,088.

To all whom it may concern:

Be it known that I, ADOLPH PETELER, a citizen of the United States,residing at 1&7

Denhofi Avenue, Freeport, county of Nassau, and State of New York, haveinvented certain new and useful Improvements in Lifting-Jacks withRotatable Cams, fully described and represented in the followingspecification and the accompanying drawings, forming a part of the same.

The present invention relates to a lifting jack having a rack upon theedge of the lifting-bar, a lifting-pawl pivoted to a liftinglever, and aholding-pawl for retaining the lifting-bar when elevated step by step bythe lifting-pawl.

The object of the invention is to furnish means constructed with a smallnumber of parts for actuating the lifting-pawl and the holding-pawl soas to lift the lifting-bar at pleasure, to lower it step by step, or toclear both pawls from the rack so that the lifting-bar may be raised orlowered to any extent in a single movement.

These objects are attained by projecting a stud from one side of eachpawl, and pivoting a rotatable cam upon the casing of the jack adjacentto each pawl, the cam be ing formed of flat sheet-metal with anecoentrio edge between its pivot and the said pawl, and the cams beinglinked to one another by a slotted connection, and connected by a;spring which presses them normally in the same direction, to hold bothpawls in an inoperative position, which permits the lifting bar to beraised and lowered by hand.

The operation of the invention will be understood by reference to theannexed drawing, in which Figure 1 is a side elevation of the jack withthe cover A to the gear-box removed; Fig. 2 is an edge view of the samewith the socket for the liftinglever broken off close to the casing;Fig. 2 is a section on line 3,-3 in Fig. 1; and Fig. 3 is'a section ofthe same in section on line o-'v in Fig. 5. Fig. 4: is a diagram showingthe position of the parts adapted, when no load is upon the lifting-bar,to drop the entire lifting-bar by raising and lowering thelifting-lever; and Fig. 5 is a diagram showing the parts disposed forlowering the lifting-bar step by step.

a designates the lifting-bar formed with a rack of teeth a upon one,edge.

Fig. 1 shows a casing Z) in which the lifting-bar is moved andwhich, asshown in Fig. 2, is formed upon one side with a housing which contains achamber 0 at one edge of the casing, and a chamber 0 at one side of thecasing, with a partition d between the two chambers.

The holding-pawl or detent e is pivoted upon the partition in the upperpart of the chamber cby a pivot 01., and the socket f for thelifting-lever is pivoted in the bottom of the chamber upon a fulcrum g,and

has the lifting pawl e pivoted to a pin 9.

upon its inner end.

The pivot a for the detent 6 extends through the outer wall of thecasing and the partition 03 'into the chamber 0 where it forms a fulcrumfor a wire-spring having leaves or free ends a, 2 applied to the outersides of studs w-m upon the pawls to press them normally toward the rackto engage its teeth a. This pivot 72 has a head a to retain the coil ofthe wire spring in place, and the pivot is a little larger in thechamber 0 than where it crosses the chamber 0, thus forming a shoulderto hold the head a ata fixed distance from the partition.

A stud w is projected from the pawl 6 through an opening or slot 4) inthe partition, to be actuated by a cam h in the chamber 0, and acorresponding stud w is extended from the pawl 6 through an opening 4/in the partition, to be actuated by a cam z. i

These cams are formed, as shown in Figs. 1 and 3, of fiat sheet-metal,which permits them to be stamped accurately to the desired form at thelowest possible cost, and are pivoted respectively upon pivots a and u.

The pivot 11; of the holding-pawl c is fixed,

and the cam it has an eccentric edge between its pivot and the stud x,which operates to press the pawl 6 out of the rack when the cam isturned upward.

The two cams are connected by a link y attached to them farther from thefulcrums of the cams than their eccentric edges, the link being jointedto a pin 7: upon the plate of the cam 72, and its lower end beingfurnished with a pin Z which is fitted to a slot m in the plate of thelower cam.

The plate of the lower earn 2' is extended beyond the slot on to form afinger-piece by which the lower cain may beset in two differentpositions in which it engages respectively stops p and 29 shown in Fig.1, upon the side of the chamber 0.

Lever-arms Q and upon the cam-plates are extended reversely from thepivots u and u of the two cams and connected by a coiled spring 7* whichoperates to press the two cams in the same direction; that is, upwardlytoward the studs upon the respective pawls, and with suliicient force tocause the retraction of the pawl e from the rack when the latter is notloaded.

The cams are provided to force the pawls away from the teeth a inlowering the rack, which in the case of the holding-pawl is effected byturning the eccentric edge of the cam against the stud a" of the pawl,as shown in Fig. 4:.

In the case of the lifting-pawl e the withdrawal is effected by lockingthe cam (by means of the finger 72) in position to intercept the stud mof that pawl when it is moved downward by the lifting-lever.

The operation of the parts is as follows:

hen the finger p is engaged with the lower stop 32 it stretches orextends the spring 1 and its tension draws the cam h forcibly upward anddraws the pivot Z up wardly in the slot m, as shown in Fig. 1.

In this adjustment of the parts, the oscillation of the handover throughits entire range of movement effects the lifting of the lifting-bar stepby step, the cams clearing the studs a. and .r' and having no effectupon the pawls.

The holdingpawl therefore slips over each tooth as the lifting-pawlelevates the lifting-bar, and engages the following tooth while thelifting-pawl is lowered.

With the finger p raised into contact with the upper step 32 as in Fig.4, the liftingbar may, if loaded, be lowered step by step, as the loadupon the lifting-bar holds the lifting-pawl in engagement with thenearest tooth, so that it cannot be forced out of the teeth by theaction of the earn 2'.

As the stud of descends under such conditions it pushes the cam and itsfinger 39 downwardly, and also draws the care 7L downward by thelink-connection thereto, as shown in Fig. This permits the spring .2 topress the pawl 0 into the rack as each tooth is lowered.

ll ith similar disposition of the parts, the lifting of the hand-lever,when the liftingbar is not loaded, w iolly releases the liftingbar, asit causes the spring 0 to raise the cam h, as shown in Fig. i, toretract the pawl e, and also draws the stud as into contact with thecam-face i, so that the liftingpawl e is also retracted, as shown inFig. 5.

It will be understood that the spring 2 or 2 does not exert asur'licient pressure to move the pawls into the teeth of the rack whenopposed by the cams, and that the cams are held in their workingposition only, by the coiled spring r. Such spring exerts force enoughto hold the cams (when in operation) so that they may retract the pawlsin opposition to the pressure of the wire-spring e, a.

In brief, the lifting-bar is raised step by step by pulling the camsdownward, as shown in Fig. 1, so that for the time they becomeinoperative.

To lower the lifting-bar when loaded, the finger g? of the lower cam israised to the stop 39 thus bringing the cams into operative relation;but the load on the lifting-bar and lifting-pawl preventing the cam '11from retracting such pawl. The same disposition of the parts, if thelifting-bar be unloaded, permits the clearing of the pawl entirely fromthe lifting-bar by the mere lifting of the hand-lever, as the cam zoperates to retract the lifting-pawl from the rack when the hand-leveris lifted.

Having thus set forth the nature ofthe invention what is claimed hereinis:

1. A lifting jack having a lifting-pawl and a holding-pawl with a studupon one side of each pawl, a rotatable cam pivoted adja cent to eachpawl with an eccentric edge adapted, when turned upon its pivot, to drawthe pawl out of the rack, and an extensioniinger integral with one ofthe cams for moving the cams and locking them in an .per ative orinoperative position.

2. A lifting jaclr having a lifting-pawl and a holding-pawl with a studupon one side of each pawl, a rotatable cam pivoted adjacent to eachpawl with an eccentric edge adapted, when turned upon its pivot, to drawthe pawl out of the rack, a link having a slotted connection with thecams, and a finger extended from one of the cams for holding the cams ineither an operative or inoperative position.

3. A lifting jack having a lifting pawl and a holding pawl with a studupon one side of each pawl, a rotatable cam pivoted adja cent to eachpawl with an eccentric edge adapted to draw the pawl out of the rack,and a single spring connecting the cams and operating to hold themnormally in a pawlshifting position.

4i. A lifting jack having a lifting-pawl and a holdingpawl with a studupon the side of each pawl, a rotatable cam pivoted adjacent to eachpawl with an eccentric edge adapted to draw the pawl out of the rack,lever-arn1s extended reversely from the pivots of the cams, and a springconnecting 7 "the said arms and operating to hold the pawlsin anoperative position.

5. A lifting jack having a lifting-pawl and aholding-pawl with a studupon one side of each pawl, a cam pivoted adjacent to each pawl andformed of flat metal with an eccentric edge adjacent to the pivot tobear upon a pawl-stud, links connecting the cams at points farther fromtheir pivots than the eccentric edges, a spring connected to the camsand pressing them normally in the same direction, and a finger formoving and lockin the cams. V

in testimony whereof I have hereunto set In hand. e

y ADOLPH PETELER.

